Stretch-shrink indicating apparatus



Feb. 1965 R. c. STRANDBERG 3,169,297

STRETCH-SHRINK INDICATING APPARATUS Filed Dec. 21, 1961 EL 5673916 POWEE i sou/ace ..L .L L%

/ 09 To' Control Mechanism PDZ A INVENTOR Robert C.Strundberg ATTORNEY United States Patent g 3,169,297 STRETfIH-fiHRENK llNDlQATlNG APPARATUS Robert C. Strandherg, Greensboro, N.C., assignor to Strandberg Engineering Laboratories, lino, Greensboro, Nil, a corporation of North Carolina Filed Dec. 21, 1961, Ser. No. 161,082 7 Claims. (ill. 2ti-2) This invention relates to new and useful improvements in apparatus for detecting and indicating the percentage of stretch or shrinkage of av continuous web or strand moving through a processing machine. the detecting and indicating apparatus of the invention is also adapted to actuate a suitable control mechanism for maintaining the stretch or shrinkage within predetermined limits. I

In the warp sizing of yarn on a slasher, for example, the yarn is first immersed in a liquid starch bath and, after passing through squeeze rollers, it is dried, as for example, by coming in contact with heater rollers or cylinders. Both yarn and fabric of natural or synthetic fiber content tend to stretch under tension to a greater extent when wet than when dry. Conversely, natural or machine introduced compressive shrinkage occurs when the material is being dried. The amount of stretch or shrinkage introduced into a warp or fabric by a textile machine is of importance. Slasher warp strength and weavability are influenced by stretch, and the amount of pro-shrinkage is highly significant in finishing textiles.

The principal object of the invention is to conveniently and accurately detect and indicate the percentage of stretch or shrinkage in a continuously moving strand or web and, through an associated control mechanism, to hold the stretch or shrinkage within predetermined limits, without the necessity of periodically interrupting the movement of the strand or Web for stretch or shrinkage measuring purposes.

An important feature of the invention resides in its arrangement and operation which exists as a function of the continuous movement of the strand or web, so that the apparatus is fully self-contained and does not require an external power source.

Other features and advantages of the invention will become apparent from the following'description taken in conjunction with the accompanying drawings, wherein like characters of reference are used to designate like parts, and wherein:

FIGURE 1 is a diagrammatic illustration of a strand or web processing machine, showing the stretch-shrink indicating apparatus of the invention in association there with;

FIGURE 2 is a wiring diagram of the apparatus; and

FIGURE 3 is a diagrammatic illustration of the logarithm generating characteristics of the diode-resistance combination used in the apparatus. 7

Referring now to the accompanying drawings in detail, particularly to FIGURE 1, the strand or web being processed is indicated by the reference numeral 18 and is shown as moving continuously in the direction of the arrows, first passing through a wetting agent or a sizing solution, as for example, a liquid starch bath l1 and then through squeeze rolls 12 driven by an electric motor operated variable speed drive 13. The electric motor operated variable speed drive 13 may comprise As such,

snare? Patented Feb. 16, 1965 an electric motor prime mover having a rheostat connected in circuit with the motor armature or held winding, and a small reversible motor the shaft of which op erates the rheostat in the. motor armature or field winding. A speed control reversing switch Ed, the function of which is subsequently further described, determines the direction of rotation of the reversible motor which controls the rheostat in the armature or field winding of the electric motor prime mover and thus controls the speed of the electric motor prime mover.

The variable speed drive meansl3, per se for changing the speed imparted to the squeeze rolls l2 and generator G may be of a conventional type and is not considered to be novel to this invention. From the rolls 12 the strand or web in passes around a plurality of suitably heated cylinders or rollers 14 where it is subjected to drying, and eventually passes over a roll 15 to a loom beam or other take-up 16.

The stretch-shrink apparatus utilizes two direct current generators G and G the former of which is driven by the motor 13 in synchronization with the rolls 12, while the latter is driven from the roll 15. The drive arrangement is such that in the absence of stretch and shrinkage in the strand or web it), the movement of the strand or web rotates armatures of the generators G and G at the same speed. However, if the web is stretched during its passage over the drying rolls M,

the generator G is driven faster than the generator wherein X is the percentage of stretch expressed as a positive number or the percentage of shrinkage expressed as a negative number, and S and S are, respectively, the speeds of the generators G and G In terms of output voltages V and V of the respective generators G and G the equation becomes where V V is a number greater than 1 in the instance of stretch or less than 1 in the instance of shrinkage.

The generators G and G are connected to a suitable, single coil meter 17 which is arranged to measure the difference in the voltage output of the two generators and the meter polarity is made to accommodate either stretch or shrinkage.

As indicated in FIGURE 2, the generators G and G are connected to the meter 17 in circuit with two silicon diodes D and D and a resistance 18, and the voltage developed across the diode D is a logarithmic function of the voltage output V of the generator G which is driven at the speed 8;. Similarly, the voltage developed across the diode D is a logarithmic function of the voltage output V of the generator G which is driven at the speed S The logarithm generating characteristic of the dioderesistance combination is exhibited in the region of very low current magnitudes as illustrated in FIGURE 3. As the current through the diode D increases, the voltage drop V across the diode increases only slightly in relation to large increases in the voltage source V.

Referring again to the aforementioned equation 1 the meter 17 may be calibrated in terms of positive percent stretch and negative percent shrinkage, so that the number 1 in the equation may be dropped and the voltage applied to the meter becomes The meter 17 may be equipped with a suitable stretch set-point controller 19 in circuit with a suitable speed control reversing switch 20 for the electric motor operated variable speed drive 13, so that the stretch or shrinkage of the web may be automatically maintained within predetermined limits.

While in the foregoing there has been described and shown the preferred embodiment of the invention, various modifications may become apparent to those skilled in the art to which the invention relates. Accordingly, it is not desired to limit the invention to this disclosure and various modifications and equivalents may be resorted to, falling within the spirit and scope of the invention as claimed.

What is claimed as new is:

1. The combination of a textile machine for processing a continuously running web and the like, said machine including web sizing means, web drying means and web take-up means, and an electrical stretchshrink indieating and control apparatus comprising a first voltage generator driven by the running movement of the web at a point between said sizing means and said drying means, a second voltage generator driven 'by the running movement of the web at a point between said drying means and said take-up means, the voltage output of said generators being directly proportional to their respective speeds, first and second logarithmic function producing means connected respectively with said first and second voltage generators for converting the output voltages of said voltage generators to logarithmic functions thereof, a single coil meter in circuit with said first and second logarithmic function producing means for measuring the difference in their voltage output, an electric motor operated variable speed drive for imparting running movement to said web, and automatic control means in circuit with said motor and with said first and second logarithmic function producing means and responsive to variations in the difference in voltage output of said first and second logarithmic function producing means for maintaining the stretch-shrink factor of the web within predetermined limits.

2. The combination of a textile machine for processing a continuously running web and the like, said machine including web sizing means, Web drying means, Web take-up means, web engaging means for imparting running movement to said web disposed at a point betwen said sizing means and said drying means, an electric motor operated variable speed drive for drivin said Web engaging means, and an electrical stretch-shrink indicating and control apparatus comprising a first voltage generator driven by the running movement of the web at a point between said sizing means and said drying means, a second voltage generator driven by the running movement V cz log V 10g V 01 of the Web at a point between said drying means and said take-up means, the voltage output of said generators being directly proportional to their respective speeds, first and second logarithmic function producing means connected respectively with said first and second voltage generators for converting the output voltages of said voltage generators to logarithmic functions thereof, a single coil meter in circuit with said first and second logarithmic function producing means for measuring the difference in their voltage output, and automatic control means in circuit with said motor and with said first and second logarithmic function producing means and responsive to variations in the difference in voltage output of said first and second logarithmic function producing means for maintaining the stretch-shrink factor of the web Within predetermined limits.

3. The combination of a textile machine for processing a continuously running web, and an electrical stretchshrink indicating and control apparatus comprising a first voltage generator driven in synchronism with the running movement of the web at a point near the entrance to said textile machine, a second voltage genera tor driven in synchronism with the running movement of the web at a point near the exit of said textile machine, the voltage output of said generators being directly proportional to their respective speeds, first and second logarithmic function producing means connected respectively with said first and second voltage generators for converting the output voltages of said voltage generators to logarithmic functions thereof, a single coil meter in circuit with said first and second logarithmic function producing means for measuring the difference in their voltage output, an electric motor operated variable speed drive for imparting running movement to said web, and automatic control means in circuit with said electric motor and with said first and second logarithmic function producing means and responsive to variations in the difference in voltage output of said first and second logarithmic function producing means for maintaining the stretch-shrink factor of the web within predetermined limits.

4. The combination as set forth in claim 3 wherein said first and second logarithmic function producing means comprise first and second diodes in circuit with the respective first and second generators and said meters, and a common reistance between said generators and said diodes, the voltage developed across each diode being a logarithmic function of the voltage output of its respective generator.

5. The combination as set forth in claim, 4 wherein each of said diodes comprises a silicon diode.

6. The combination of a textile machine for processing a continuously running web, and an eiectrical stretchsh-rink control apparatus comprising a first voltage generator driven in synchronism with the running movement of the web at a point near the entrance to said textile machine, a second voltage generator driven in synchronism with the running movement of the web at a point near the exit of said textile machine, the voltage output of said generators being directly proportional to their respective speeds, first and second logarithmic function producing means connected respectively with said first and second voltage generators for converting the output voltages of said voltage generators to logarithmic functions thereof, an electric motor operated variable speed drive for imparting running movement to said web, and automatic control means in circuit with said electric motor and with said first and second logarithmic function producing means and responsive to variations in the difference in voltage output of said first and second logarithmic function producing means for maintaining the stretch-shrink factor of the web within predetermined limits.

7. The combination as set forth in claim 6, wherein said first and second logarithmic function producing means comprise first and second diodes in eir-ouit with the respective firstand second generators, and a common re- 2,007,828 Johnson July 9, 1935 McBa'ne May 5, McConnell May 16, Stienen Oct; 24-, Martin June 3, Kenny July 8, Rogers Mar. 17, Rendel' Aug. 17, Rendel et a1. 2; Aug. 17, Reed Oct. 10, Scheu Feb 

1. THE COMBINATION OF A TEXTILE MACHINE FOR PROCESSING A CONTINUOUSLY RUNNING WEB AND THE LIKE, SAID MACHINE INCLUDING WEB SIZING MEANS, WEB DRYING MEANS AND WEB TAKE-UP MEANS, AND AN ELECTRICAL STRETCH-SHRINK INDICATING AND CONTROL APPARATUS COMPRISING A FIRST VOLTAGE GENERATOR DRIVEN BY THE RUNNING MOVEMENT OF THE WEB AT A POINT BETWEEN SAID SIZING MEANS AND SAID DRYING MEANS, A SECOND VOLTAGE GENERATOR DRIVEN BY THE RUNNING MOVEMENT OF THE WEB AT A POINT BETWEEN SAID DRYING MEANS AND SAID TAKE-UP MEANS, THE VOLTAGE OUTPUT OF SAID GENERATORS BEING DIRECTLY PROPORTIONAL TO THEIR RESPECTIVE SPEEDS, FIRST AND SECOND LOGARITHMIC FUNCTION PRODUCING MEANS CONNECTED RESPECTIVELY WITH SAID FIRST AND SECOND VOLTAGE GENERATORS FOR CONVERTING THE OUTPUT VOLTAGES OF SAID VOLTAGE GENERATORS TO LOGARITHMIC FUNCTIONS THEREOF, A SINGLE COIL METER IN CIRCUIT WITH SAID FIRST AND SECOND LOGARITHMIC FUNCTION PRODUCING MEANS FOR MEASURING THE DIFFERENCE IN THEIR VOLTAGE OUTPUT, AN ELECTRIC MOTOR OPERATED VARIABLE SPEED DRIVE FOR IMPARTING RUNNING MOVEMENT TO SAID WEB, AND AUTOMATIC CONTROL MEANS IN CIRCUIT WITH SAID MOTOR AND WITH SAID FIRST AND SECOND LOGARITHMIC FUNCTION PRODUCING MEANS AND RESPONSIVE TO VARIATIONS IN THE DIFFERENCE IN VOLTAGE OUTPUT OF SAID FIRST AND SECOND LOGARITHMIC FUNCTION PRODUCING MEANS FOR MAINTAINING THE STRETCH-SHRINK FACTOR OF THE WEB WITHIN PREDETERMINED LIMITS. 